The invention relates to a method of displaying images on a subfield driven matrix display device, including plasma display panels (PDPs), plasma-addressed liquid crystal panels (PALCs), liquid crystal displays (LCDs), Polymer LED (PolyLEDs), Electroluminescent (EL), used for personal computers, television sets, etc.
The invention further relates to a display device comprising a receiving circuit for receiving luminance data comprising original luminance value data of pixels, the display device further comprising a display panel comprising a set of lines r1 . . . rM, and a driver circuit for supplying line luminance value data to said lines, said lines being grouped in sets of neighboring or adjacent lines, wherein a common value for the multiple line addressed sub-fields is addressed simultaneously to a set of lines.
Methods of displaying luminance levels in a plasma display panel are known from EP 0 890 941. In these methods the high weight subfields are addressed for each display line, and the low weight subfields are addressed for only part of the display lines. These methods allow e.g. a reduction of the address period by a factor of two for doubled subfields, or depending on the number of doubled subfieldsxe2x80x94e.g. of the total address period by 25%, thereby allowing a substantial increase of the duration of the sustain period.
Also in EP-A-0 874 349 a process for addressing bits on more than one line of a plasma display is disclosed.
In the method disclosed in EP-A-0 953 956 and EP-A-0 880 125 an improved method for displaying grey levels with reduced error is disclosed. Analog grey values are distributed over a number of pixels. Both spatial and temporal dithering as such are disclosed.
It is an object of the invention to provide a method of displaying successive image frames or fields on a display device so that the picture quality is improved, more particular so that resolution is improved and motion artifacts are avoided as much as possible.
The present invention provides a method of displaying successive image frames or fields on a matrix display device, said display device comprising a predetermined number of display lines each including a predetermined number of picture elements, wherein said pixels are coded in subfields and said matrix display device is driven by said subfields and wherein the luminance values to be displayed are derived from original luminance values having a higher number of bits or grey levels than the number of bits or grey levels to be displayed by a pixel element, said method further comprising the following steps:
using one or more of the subfields with the lowest or lower weight(s) in a dithering process; and
addressing two or more lines simultaneously for supplying respective common values to one or more subfields having a higher weight than said lowest or lower weight(s) of the pixels of said lines.
According to the present invention the partial line doubling is shifted to less significant subfields, however, excluding the one, two or more least significant subfields so that these subfields can be used for dithering.
Various dithering methods are known as such. In a preferred embodiment use is made of Floyd-Steinberg error diffusion.
It is possible to use averaging or copying of bits (subfield) for partial line doubling (excluding the least significant subfield(s)). However it is preferred to use further correction methods to further eliminate image errors due to the dithering and/or the partial line doubling.
In a further preferred embodiment addressing of a set of adjacent lines is performed differently for successive frames or fields, and/or for different regions of the display device and/or for different subfields.
By grouping the lines differently into successive frames and to different areas of the display, the address period is further reduced, avoiding loss of resolution.